Fuel Gauge & Wiring Testing

I need some help. I've read over all the forums and I'm still a bit stuck. My fuel gauge always shows empty. Following the advice of many others I started with the fuel sending unit. The unit itself is fairly new and with a multimeter it registered about 16 ohms on full and 119 ohms empty. Knowing it works I figure it has to be the fuel gauge or the wiring. I pulled the gauge cluster to get access to the fuel connectors but I'm unsure how to test it. Also, I read that sometimes the issue can be improper grounding. I don't have any electrical experience so detailed instructions are super helpful. I did do a couple of tests with the multimeter on the back of the fuel gauge. I'm posting the pics. Maybe someone can tell me if based on these numbers the gauge is functioning properly. Last, with access to the back of the fuel gauge is there a way to test it to make the needle move? Thanks for your help.

So I tried following the guide and got mixed readings. I decided to pull the fuel gauge and hook it directly up to the sending unit. After a few wiring combinations I was able to get it to work and show the correct fuel amount. This is great because I know that the sending unit and gauge work correctly. It must be an issue with the wiring. Any ideas on what to do next?